(a) Technical Field
The present application relates to a display device and a driving method thereof. More particularly, the present application relates to a display device for improving visibility and a driving method thereof.
(b) Description of the Related Art
Display devices such as a liquid crystal display (LCD) and an organic light emitting device generally include a display panel that includes a plurality of pixels including switching elements and a plurality of signal lines, a gray voltage generator that generates a gray reference voltage, a data driver that uses the gray reference voltage to generate a plurality of gray voltages and applies gray voltages corresponding to an input image signal among the generated gray voltages to a data line as a data signal, and the like.
Among those, the liquid crystal display includes two display panels including pixel electrodes and opposed electrodes, and a liquid crystal layer disposed therebetween and having dielectric anisotropy. The pixel electrodes are arranged in a matrix type and are connected to switching elements such as a thin film transistor (TFT), and the like, and sequentially receive a data voltage row-by-row. The opposed electrodes are formed over the display panel and are applied with a common voltage (Vcom). A voltage applied to the pixel electrodes and the opposed electrodes generates an electric field in the liquid crystal layer, and the strength of the electric field is controlled to control transmittance of light transmitting through the liquid crystal layer, thereby obtaining desired images.
The liquid crystal display may have reduced side visibility compared to front visibility. In order to solve this problem, a method of dividing one pixel into two subpixels and making voltages of the two subpixels different has been proposed. Regarding the method, for each single piece of image data, voltages caused by different gamma curves must be input to two subpixels. To supply the voltages induced by the respective gamma curves to the two subpixels, signal lines such as a gate line or a data line must be added or a transformation means for transforming the voltage supplied to one subpixel must be further formed.
To make side visibility close to front visibility, in the case of a liquid crystal display in which one pixel is divided into two subpixels and the voltages applied to the two subpixels are differentiated, luminance is increased in a low gray or a high gray such that the gray expression is difficult at the side and the display quality may be deteriorated. Also, when a transmittance change is not clear according to a gray change of the image signal, the target gray change is not expressed such that the display deterioration may be generated.
Further, to divide a pixel into a plurality of subpixels and allow the subpixels to receive voltages caused by different gamma curves, signal lines such as the gate line or the data line and a corresponding driving circuit must be added, a transformation means such as a switching element for transforming the voltage supplied to the subpixel must be further formed, or a mask must be added to add a pattern. Therefore, the process for manufacturing a display device becomes complicated, and an opening through which the light may pass is made narrower by an additional pattern or an additional switching element so transmittance may be deteriorated.
The above information disclosed in this Background section is only for enhancement of understanding of the background and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.